Q. Why do we need purgatory?
A. Sacred Scripture and Tradition repeatedly affirm that God’s ultimate intention is for us to become perfect as He is perfect (see Mt 5:48). Why?
Because God wants us to live forever in friendship with Him, and He Himself is completely holy — without sin or weakness of any kind. To see God face-to-face in heaven, and to know, love, and enjoy Him there fully forever, we must be like Him (see Heb 12:14; 1 Jn 3:2-3).
In fact, heaven simply wouldn’t be heaven unless those who lived there had been perfected. If we were to bring along with us all the sins and weaknesses we have in this life, heaven would be just as full of troubles as our life on earth—troubles that would last for eternity.
Didn’t Christ die to forgive us our sins and save us? Yes! But even those who have escaped, through His infinite merits, the penalty of hell — an eternity without God — find that sin has countless other consequences. It disorders our souls. It injures others. It leaves us overly attached to things we have chosen to love more than we love God.
If we’re to live with God forever, then, repairs and reparations are necessary; that is, we must be healed and make amends. If we’re selfish, we must learn to love. If deceitful, we must learn to tell the truth. If addicted, we must break the addictions. And if bitter, we must forgive.
Even so, whether in this life or the next, God doesn’t wave a magic wand, bypassing our free will, to fix the situation. Instead, we undergo a procedure to undo the consequences of what we’ve done. This process, requiring our cooperation with grace, begins on earth. Through doing penance and accepting in faith the inescapable sufferings of the present life, we can be purged of sin’s effects and grow in holiness.
Nevertheless, few of us are perfect when we leave this world. We still need some “cleaning up,” a painful but purging “fire,” as the Scripture calls it (see 1 Cor 3:14–15). That process is what we call purgatory.